Its because to send an email you have to be a paid member.........and lots of people on here are free members so they can only use the "wink"!
I suppose you have realised now that the men who have joined here for whatever reason can't/won't pay for membership and hope that they'll get lucky at least once by bombarding all the women with winks.
Makes a joke of the reason men have joined this particular site and they are unable to pay just for membership,let alone meet a woman,go on dates etc!
I'm a paid member but when my membership ends I log off and hide my profile instead of being a silent member.
Anyway,winks are for women to let the MEN step up and message them.
Just my two cents.